The last fire crews left Trademark Metals Recycling in the Port of Tampa about 12:30 a.m., said Capt. Lonnie Bennefield, a spokesman for the department. Fire Rescue was called to the scene around 3:30 p.m. Tuesday to douse the burning pile of household machinery and scrap iron, which was about 100 yards long.

The flames caused a plume of black smoke that could be seen in Tampa and St. Petersburg.

The cause of the fire wasn't immediately known and likely won't be determined because evidence was disturbed while firefighters were battling the fire, Bennefield said.

But fire investigator Joe Hotz ruled the fire an accident, saying it was highly likely it was caused by a spark from moving metal, according to Fire Rescue.